[MM-15639] Add config setting to explicitly define which IP headers are trusted (#10907)

* Add config setting to explicitly define which IP headers are trusted

* fix variable shadowing

* Optimize code flow; Add Ratelimit test for header set

* Extend Ratelimit tests

* Add additional unit tests

* Structured logging

app/ratelimit.go

@@ -23,9 +23,10 @@ type RateLimiter struct {
 	useAuth              bool
 	useIP                bool
 	header               string
+	trustedProxyIPHeader []string
 }
 
-func NewRateLimiter(settings *model.RateLimitSettings) (*RateLimiter, error) {
+func NewRateLimiter(settings *model.RateLimitSettings, trustedProxyIPHeader []string) (*RateLimiter, error) {
 	store, err := memstore.New(*settings.MemoryStoreSize)
 	if err != nil {
 		return nil, errors.Wrap(err, utils.T("api.server.start_server.rate_limiting_memory_store"))
@@ -46,6 +47,7 @@ func NewRateLimiter(settings *model.RateLimitSettings) (*RateLimiter, error) {
 		useAuth:              *settings.VaryByUser,
 		useIP:                *settings.VaryByRemoteAddr,
 		header:               settings.VaryByHeader,
+		trustedProxyIPHeader: trustedProxyIPHeader,
 	}, nil
 }
 
@@ -57,10 +59,10 @@ func (rl *RateLimiter) GenerateKey(r *http.Request) string {
 		if tokenLocation != TokenLocationNotFound {
 			key += token
 		} else if rl.useIP { // If we don't find an authentication token and IP based is enabled, fall back to IP
-			key += utils.GetIpAddress(r)
+			key += utils.GetIpAddress(r, rl.trustedProxyIPHeader)
 		}
 	} else if rl.useIP { // Only if Auth based is not enabed do we use a plain IP based
-		key += utils.GetIpAddress(r)
+		key += utils.GetIpAddress(r, rl.trustedProxyIPHeader)
 	}
 
 	// Note that most of the time the user won't have to set this because the utils.GetIpAddress above tries the